Telephone-exchange system.



H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR. I8. I9l5- 1 ,297,1 0U Pfi tel lt ed Mar. 11, 1 919.

T ToGeneraIor UNITED STATES PATENT OFFICE.

HENRY PETER CLAUSEN, OF MOUNT VERNON, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORA- TION or NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed March 18, 1915. Serial No. 15,358.

To all whom it may concern: l

Be it known that I, HENRY P. CLAUsnN,

a citizen of the United States, residing at Mount Vernon, in the county of West chester and State of New York, have invented certain new and useful Improvements inTelephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems of the central energy type, the object of this invention being to provide improved signaling means for such systems.

In accordance with a feature of this in vention means are provided whereby in central energy telephone exchange systems of the two-wire type, when a subscriber has initiated a call, the connection of an ex change connecting circuit with the calling line causes the operation of signaling means at the exchange.

In accordance with another feature of this invention there is provided a relay associated with a link circuit and energized over a circuit including a portion of a talking strand of the line during the association of the link with acalling line, and means cooperating with said relay to cause the op eration of recall signaling means at the exchange to furnish a signal to the operator upon the hanging up and a subsequent removal of a connected calling subscribers receiver. y

This invention is illustrated in the accompanying drawing in which all apparatus is shown in its normal and unactuated posif tion.

There is shown in the drawing a telephone exchange system containing one embodi ment of this invention and comprising the usual subscribers stations A and B', and a cord circuit C located at the central oifice for interconnecting the subscribers stations. It is believed that this invention will be fully. understood from a description of the operation of the system shown in the drawing, and it will be so described.

Supposing subscriber A wishes to con verse with subscriber B, A removes his receiver from the switchhook, thereby complating a circuit from battery 5 through the winding of line relay 6, contact 7 of cutoff relay 8-, line wires 9 and 10, and contact 11 of cutoff relay to ground. Current in this 6, completing a cir-' path actuates line relay cuit for line signal 12.

The operator, observing the line signal 12, inserts the answering plug in the jack indicated by this line signal, thereby closing a circuit from battery 15 through the winding of relay 16, ring contacts of the answering plug and jack and the winding of cutoff relay 8 to ground. Current in this path actuates relay 16 which closes its con tact 17, completing a circuit from battery 18 through the winding'of relay 19, con tact 20 thereof, contact 21 of relay 22, contact 17 of relay 16 and contact 23 of the listening key 24; to ground. There is also completed a path for supervisory signal 31 from battery 30. opens its contact 20'and closes its contacts 25 and 26.. The closure of'contact 25 establishes a locking circuit for relay 19, through contact 17 of relay 16 and contact 23 of listening key'2 1. The closure of con tact 26 closes a circuit from battery 30, through supervisory signal 31, contact 26 of relay 19, and contact 27 of relay 28 to ground. It is to be observed that a circuit from battery 32, through the winding of relay 28 and interrupter 33 to ground, interinittently energizes relay 28, thereby causing its contact 27 to be closed intermittently.

-The circuit which has hereinbefore been of contact 27 of relay 28, at this time, has

no effect on the signal 31. When the answering plug was inserted in the jack indicated by line signal 12 the local circuit Relay 19 in operating,

Patented Mar. 11, 1919.

established thereby and hereinbefore traced included the winding of cutofl" relay 8. The adjustment of this relay however is such thatit does-not operate until after relay 16 operates. Upon the operation of cutofl relay 8, its contacts 7 and 11 are opened and 'its contacts 35 and 36 are closed, connecting the line wires 9 and 10 with the ring and tip contacts of the answering jack, respectively. Upon the closure of contacts 35 and 36 of cutoif relay 8 a circuit is established from battery 15, through the winding 'of relay 16, ring contacts of the answering' plug and ack, line wires 9 and 10, contacts of the jack and answering plug and the winding of relay to ground. Current in this path actuates relay 22 which opens its contact 21, interrupting the circhit which is in parallel with contact 26 of relay 19 and contact 27 of relay 28. Thereafter the circuit through the signal 31 is intermittently closed, thereby causing this signal to intermittently flash to give a signal to the operator.

The operator now actuates listening key 2% and connects the operators telephone set across the limbs of the cord circuit and asks the desired number of the calling subscriber. in operating listening key 2%, contact 23 thereof is opened, thereby interrupting the hereinbefore traced locking circuit 0t relay 19, thereby permitting relay 19 to release, which operation opens at contact 26 the hereinbei'oretraced flashing circuit for supervisory signal 31. Supervisory signal 31 is thereby effaced. Finding the desired.

number to be that of subscriber B, the calling plug is inserted in the jack corresponding to Bs line, completing a circuit from battery eO' through the winding of relay 4-1, ring contacts of the calling plug and jack and .the winding oi cutoff relay 1-2 to ground. Current in this path actuates relay ll which opens its contact as and closes its contacts a l and 45. Current in this path also actuates cutoit relay d2 which cuts line relay 16 from line wires ll and as, and connects these line wires to the tip and ring contacts of the jack. Ihe closing oi contact 45 of relay n completes a circuit from battery 50 through supervisory signal 51, contact 52 of relay T6 and contact e5 of relay a1 to ground, operating supervisory signal 51. A circuit is also completed from battery 53, through the winding of relay 5 1, resistance and contact 1-5 of relay ll to ground. Relay 5% however is not operated, for there is a short circuit about the winding of this relay which may be traced from battery 56 through contact 57 of relay 58, contact 59 of relay 5% to the resistance 55. The closure of contact d4: of relay 41 completes a circuit from a source of ringing current 65, through the winding of relay 58, contact at of the relay ll, contact 66 of the relay 5%, tip contacts oi the calling plug and jack, contact 67 of cutoilt relay a2, line wires 4:8 and 47, contact 68 of cutoff relay e2, ring contacts of the jack and calling plug, contact 69'ot the relay 54, resistance 70 and battery 71 to ground. Ringing current through the above traced circuit operates ringer 72 at the substation B. Subscribei' B, in removing the receiver from the switchhook in response to the operation of ringer 72 completes a path of low resistance for the ringing current. It may be noted here that relay 58 is marginal and will not operate when in sauce with the ringer 72 and condenser 73 at substation E, but will operate when the path of low resistance established by the switchhook contactis closed. The removal of the receiver from the switchhook at substation B therefore permits relay 58 to operate, which opens its contact 57, removing the short circuit from about the winding of relay 54: which, in responding, opens its contacts 59, 66 and 69 and closes its contacts 74, thereby closing the normal break in the tip strand of the cord circuit. The opening of contact 66 breaks the circuit through relay 58 which thereupon releases,

but the short-circuit tor the winding of relay 5% is not again established because contact 59 is open. contact 74 a circuit is established from battery a0, through winding of relay 41, ring Upon the closure of contacts of the calling plug and jack, line wires a7 and as, tip contacts of the jack and calling plug, contact 7 1 or relay 54 and the winding of relay 7 6 to ground. Relay 76 operates, effacing supervisory signal 51.

Upon finishing the conversation, subscribers A and B restore their respective receivers to the switchhooks, whereupon relays 22 and 76 release, permitting supervisory signals 31 and 51 to operate to give disconnect signals. It the operator is not busy the answering and calling-plugs arereinoved from the jacks and all apparatus returned to normal posit on. Suppose, however, that as is frequently the case during busy periods, the operator does not immeof relay 22 closes its contact 21, thereby completing for relay 19 the hereinbefore traced circuit, whereupon relay 19 operates, completing the locking circuit for itself which has-already been traced. Upon the subsequent removal of the receiver at substation A from its switchhook, relay 22 is operated, thereby permitting supervisory signal 31 to intermittently flash in the same mannor as it is caused to flash when the answering plug is inserted in the ack of the calling subscriber. As long then as As receiver is off the switchhook the supervisory signal 31 will fiash'intermittently until the operator operates listening key 24.

It is to be noted that by utilizing the present invention, the improved signaling system may be applied to telephone exchange systems of the common battery two-wire type merely by the addition of a single relay per cord circuit and interrupter mechanism common to a position or to the exchange.

Quite often, if an operator is busy an answering plug may be inserted in the answering jack of'a calling line and then the operator may forget all about the connected calling subscriber, in which case in systems heretofore used, the subscriber obtains very poor service and waits for awhile thinkin the operator will answer but after a time nds that he must operate the switchhook a number of times to attract the attention of the operator. By using the present invention, all this annoyance and delay are avoided for the supervisory signal will flash intermittently until the listening key is operated. It will also be seen that the improved means for causing the supervisory signal to give asignal distinct in character for recall purposes overcomes many difii culties heretofore experienced when con- .nected subscriber was trying to attract the I attention'of the operator to make another call. While plurality of batteries have been referred to in this description, it is to be understood that a single battery may be substituted therefor, and such is the usual practice.

l/Vhat is claimed is:

1. In a telephone exchange system, calling and called subscribers lines, a link circuit for interconnecting said lines, flashing signaling means associated with the answering end of said link circuit, a central source of current, and .two relays cooperating when energized to start and continue the operation of said flashing signaling means to present a signal, one of said relays being energized from said source upon the connection of said link with said calling line over a path including a portion of a talking strand of said link circuit, the other of said relays being energized from said source over a path including a portion of said link and the calling line.

2. In a telephone exchange system, calling and called subscribers lines, a link circuit for interconnecting said lines, a signaling device associated with the answering end of said link circuit, interrupter mechanism and a source of current at the exchange, a relay energized over a local circuit established upon connection of said link with said calling line and includin a portion of a talking strand of said lin circuit, a relay actuated upon energization of said first relay to partially associate said signaling device, said interrupter mechanism and said source of current, and a third relay associated with said link circuit and energized over said calling line for completing said association whereby said signaling device is caused to present a signal to the operator.

3. In a telephone exchange system, calling and called subscribers lines, a link circuit for interconnecting said lines, flashing signaling means associated with the answering end of said link circuit, a central source of current, two relays cotiperating when energized to start and continue the operation of said flashing signaling means to furnish a signal, one of said'relays being energized from said source upon connection of said link with said calling line over a path including a portion of a talking strand of said link circuit, the other of said relays being energized from said source over a path including a portion of said link and the calling line, and operator controlled means for eflacing said signal.

4. In a telephone exchange system, calling and called subscribers lines, a link circuit for interconnecting said lines, recall signaling means associated with the answering end'of said link circuit, and two relays adapted to cotiperate to cause said recall signaling means to operate to present a signal, one of said relays being actuated during connection of said link with a calling ing and called subscribers lines, a two wire link circuit connecting the lines, a supervisory signaling device, interrupter mechanism, a source of current, a supervisory relay controlled from a connected station and whendcnergized connecting the source of current in circuit with the supervisory signaling device to cause continuous operation thereof to furnish a disconnect si a1, and a relay operated by the deenergizatwn of the supervisory relay to partially associate the signaling device, the interrupter mechanism and the source of current, the subsequent energization of the supervisory relay causing the completion of said association whereby the supervisory signaling device is caused to operate intermittently to furnish a recall signal.

6. In a telephone exchange system, calling and called subscribers lines, a link circuit for interconnecting the lines, a signaling device, interrupter mechanism, an operating circuit for the signaling device and the interrupter mechanism, a primary relay energized upon the connection of the link circuit with one of the lines over a path including a portion of a talking strand of the f ElOU link circuit, a supervisory relay in the link circuit and controlled, over the connected g circuit and controlled over the connected line, and a secondary relay energized when the primary relay is energized and the su pervisory relay is deenergized to close a break in the openating circuit/ the subsequent energization of the supervisory relay causing the signaling device to operate intermittently.

7. In a telephone erichange system, calling and called subscrilcers lines, a link circuit for interconnecting the lines, a signaling device, interrupter mechanism, an operating circuit for the signaling device and the interrupter mechanism, a primary relay energized upon the connection of the link circuit With one of the lines over a path including a poltion of a talking strand of the link circuit, a supervisory relay in the linl:

line, a secondary relay energized when the primary relay is energized and the supervisory relay is deenergized to close a break in the operating circuit and a short circuit aboutthe interrupter mechanism While the supervisory relay is denergized the subsequent energization of the supervisory relay removing the short circuit and permitting the intermittent operation of the signaling device.

In Witness whereof, l 'hereuntc' subscribe my name this 17th day of March A. D.

FENRY CLAUSEN. 

